Marc;
Again, some great advice; I will have to mess with it some more to get it right; I will be using this neat Gear/Door sequencer from Canada, that uses your Computer and measures the travel the servo makes to open the doors and activate the airvalve, remembers it, then you dowload into the memory of the sequencer, then when you flip an on/off switch assigned to the retract channel it will only allow the servos to travel the distance that was inputed into the memory; when you first set this up you use a variable slider switch like a flap switch to articulate the gear doors and valve servo to the end points you want; after all the endpoints are keyed in and the time delay between functions, you dowload into sequencer and change the switch assignment to an on/off switch.
When you flip the switch the Sequencer does the rest.
So from what you have told me, this should all work well with the sequencer I have told you about here is the link to this sequencer; let me know what you think of it?
http://www.gccustomelectronics.ca/gdc1.html